This invention relates to a method of forming an element of a composite aerodynamic rotor blade, and in particular to a method of forming the spar layup of a composite aerodynamic helicopter rotor blade.
The present state-of-the-art as developed by the Boeing Vertol Company, the assignee of the present application, employs an automatic tape layup machine in the fabrication of many of the components of the composite aerodynamic rotor blade. The machine has proven to be a remarkable tool for the layup of complex components such as are found in helicopter rotor blades. It has, for example, demonstrated laminant repeatability and component quality previously unattainable.
At the present time the spar member of the rotor blade is laid-up by wrapping tape using the automatic tape layup machine onto a complex contoured mandrel around a sleeve of the root end of the blade and transitioning the tape outboard to form the airfoil contour directly on the complex contoured mandrel. According to current techniques the strap which forms the spar is formed by taking one tape, for example, 0.010 inches thick, and laying it on the complex contoured mandrel starting outboard, bringing the tape around the sleeve and back adjacent to the starting tape, and repeating this process until the required strap thickness is achieved. This operation requires wiping, twisting, and careful placement of each tape to conform to the layup mandrel. Because of these requirements, this present fabrication process is time consuming and, consequently, costly.
It would, therefore, be desirable to provide the existing state-of-the-art with a method of laying-up the spar member of the rotor blade utilizing the automatic tape layup machine which is less time consuming and less costly, while not sacrificing any of the quality features obtainable with the automatic tape layup machine.